The present invention is directed to a friction wedge for a railroad car truck and in particular to a friction wedge including a body having a pocket and a wear member that is adapted to be inserted into the pocket and removably attached to the body such that when the wear member becomes worn it may be removed and replaced with a new wear member.
Railroad car trucks include a pair of spaced apart side frames and a bolster that extends transversely between the side frames. The bolster is resiliently supported at each end on a respective side frame by a plurality of suspension springs. Friction wedges are used in railroad car trucks to dampen movement of the bolster with respect to the side frame of the railroad car truck. Friction wedges are often generally triangular-shaped such that the friction wedge can act as a wedge between an inclined surface of the bolster and a generally vertical wear plate on a column of the side frame. The friction wedge is wedged into engagement between the bolster and the column of the side frame by a suspension spring. Resistance to sliding movement of the friction wedge with respect to the side frame, which in turn provides dampening of bolster movement, is provided by the frictional forces generated between the friction wedge and the wear plate of the side frame column.
Prior art friction wedges sometimes include a wear pad adapted to slidably engage the wear plate of the side frame column such as disclosed in U.S. Pat. No. 2,827,987. A wear pad such as shown in U.S. Pat. No. 2,827,987 is exposed around its edges such that the wear pad is susceptible to being damaged during use after the friction wedge is installed in the railroad car truck, and is susceptible to being damaged during shipment. Such a friction wedge does not include a mechanical structure that prevents lateral sliding movement of the wear pad with respect to the plate member which supports the wear pad. The present invention overcomes these problems in the prior art.
A friction wedge for a railroad car truck having a bolster, a bolster suspension spring, and a side frame. The friction wedge includes a body having a base adapted to engage the suspension spring, an inclined wall adapted to engage the bolster, and a front face including a pocket. The pocket includes a bottom wall and a peripheral side wall extending outwardly from the bottom wall and substantially around the perimeter of the bottom wall. A wear member is adapted to be located within the pocket of the body. The wear member includes a wear pad having a first wall that is complimentarily-shaped with the bottom wall of the pocket and that is adapted to be placed adjacent to the bottom wall of the pocket. The wear member includes a generally planar second wall spaced apart from the first wall that is adapted to slidably engage the side frame of the railroad car truck. The wear pad includes a peripheral side wall that extends between the first wall and the second wall of the wear pad and that extends around the perimeter of the first and second walls. The first wall of the wear pad extends generally coextensively with the bottom wall of the pocket. The peripheral side wall of the pocket extends around the peripheral side wall of the wear pad and is located closely adjacent to the peripheral side wall of the wear pad. The wear member may include an adhesive layer located on the first wall of the wear pad which is adapted to removably attach the wear pad to the bottom wall of the pocket with a relatively weak adhesive bond such that the wear pad will remain in the pocket during installation of the friction wedge in the railroad car truck while still allowing the wear pad to be selectively removable from the pocket. Alternatively the wear member includes a protrusion adapted to be inserted into a recess in the bottom wall for removably attaching the wear pad to the body of the friction wedge. The peripheral side wall of the pocket prevents any substantial lateral sliding movement of the wear pad with respect to the bottom wall of the pocket. The peripheral side wall of the pocket also covers a substantial portion of the side wall of the wear pad and thereby protects the wear pad from damage.